TM 5-3805-258-24-1FUEL SYSTEMSYSTEMS OPERATIONvalve (7) in the large piston closes and the pressure ofthe fuel below the check valve increases. Fuel nowflows through the outlet check valve. A part of thefuel goes through outlet (4) and the remainder goesto the area above small piston (3).FUEL TRANSFER PUMP SCHEMATIC (UPSTROKE)1. Bypaaavalve. 2. Pumping spring. 3. Small piston. 4.Outlet. 5. Inletcheck valve.6. Push plate. 7. Pumpingcheckvalve.6. Outlet check valve. 9. Large piston. 10.Push rod.FUEL TRANSFER PUMP SCHEMATIC (DOWN STROKE)1. Bypaaavalve. 2. Pumping spring. 3. Small piston. 4.Outlet. 5. Inlet check valve.6. Push plate. 7. Pumpingcheckvalve.8. Outlet checkvalve.9. Large piston. 10.Push rod.As the large piston moves down, fuel from the fueltank is pulled through inlet check valve (5) into thearea between the large and small piston. The pump isnow ready to start a new cycle.Bypass valve (1) controls the outlet pressure of thefuel. If the fuel pressure goes beyond 170 to 280 kPa(25 to 40 psi), the bypass valve opens and fuel flowsto the inlet of the pump.OIL FLOW FOR FUEL PUMP AND GOVERNOROil from the side of the cylinder block goes tosupport (9) and into the bottom of front governorhousing (4). The flow of oil now goes in three differ-ent directions.A part of the oil goes to the rear camshaft bearingin fuel pump housing (5). The bearing has a groovearound the inside diameter. Oil goes through thegroove and into the oil passage in the bearing surface(journal) of camshaft (7). A drilled passage throughthe center of the camshaft gives oil to the frontcamshaft bearing and to the thrust face of the cam-shaft drive gear. Drain hole (6) in the front of fuelpump housing (5) keeps the level of the oil in thehousing even with the center of the camshaft. The oilreturns to the oil pan through the timing gearhousing.Oil also goes from the bottom of the front governorhousing through a passage to the fuel pump housingand to governor servo (2). The governor servo giveshydraulic assistance to move the fuel rack.The remainder of the oil goes through passagesto the rear of rear governor housing (3), through airfuel ratio control (1) and back into another passagein the rear governor housing. Engines that do nothave an air fuel ratio control have a cover with anoil passage to complete the oil flow. Now the oil goesinto the compartment for the governor controls.Drain hole (8) keeps the oil at the correct level. Theoil in this compartment is used for lubrication ofthe governor control components and the oil is thesupply for the dashpot.The internal parts of the governor are lubricatedby oil leakage from the servo and the oil is thrown byparts in rotation. The flyweight carrier thrust bear-ing gets oil from the passage at the rear of thecamshaft.Oil from the governor returns to the oil panthrough a hole in the bottom of the front governorhousing and through passages in the support andcylinder block.3-6